Center of Pressure lab presentation.

1. Welcome to the presentation
on
1

2. Sumaiya Tabassum
Lecturer
Department of Civil Engineering
Stamford University Bangladesh.
Supervised by,
• Mehedi Hossen Khan
• #ID: CEN 068 10152
• Nazmul Hasan Diptu.
• #ID: CEN 062 09450
• Kazi Rubayet Morshed
• #ID: CEN 062 09423
• Md. Abu Sayed Prodhan
• #ID: CEN 062 09495
• Mahamud Rejwan Sabri
• #ID: CEN 062 09444
• Md Touhidul Islam
• #ID: CEN 068 10153
Presented by,
2

3. BACKGROUND
• The center of pressureis that point where the total
some of pressure field acts one a body, causing a force to
act through that point. The resultant force and Centre of
pressure location produce equivalent force and moment
on the body as the original pressure field
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4. APPARATUS Water
Tank
Detent
Slider Stop Pin
Water
Level Scale
Rider
Weights Handle
4

5. PROCEDURE
• 1. The apparatus is placed in a
• splash tray and correctly
• leveled.
• 2. The length l and width b of the
• rectangular surface, the
• distance r from the pivot to the
• top of the surface, and the
• distance s from the hanger to
• the pivot were recorded.
• 3. The rectangular surface is
• positioned with the face
• vertical (θ=0) and clamped.
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6. • Hydrostatic Pressure Apparatus
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7. PROCEDURE
cont
4. The position of the moveable
jockey weight is adjusted to give
equilibrium, i.e., when the balance
pin is removed there is no
movement of the apparatus. The
balance pin is replaced
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8. PROCEDURE
cont
5. Water is added to the storage chamber. This
created an out-of-balance clockwise moment
in the apparatus. A mass M is added to the
hanger and water is slowly removed from the
chamber via drain hole such that the system is
brought almost to equilibrium, but now
Clockwise moment is marginally greater.
Water is slowly nodded to the storage chamber
by a dropper until equilibrium is attained. At
this condition the drain hole is closed and the
balance pin again removed to cheek
equilibrium.
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9. PROCEDURE
cont
6. The balance pin is replaced
and the values of y1, y2 and
M were recorded.
7. The above procedure is
repeated for various
combinations of depth.
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10. MAJOR
EQUATION
The magnitude of the total hydrostatic force F
will be given by
F = ρgȳA
Where, ρ = Density of fluid
g = Acceleration due to gravity
ȳ = Depth to centroid of immersed
A = Area of immersed surface
This force will act through the centre of pressure
C.P. at a distance (Measured vertically)from
point O
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11. MAJOR
EQUATION
Theory shows that
y = ȳ +
ICG
Ay
Where,
ȳ = distance from O to the centroid CG of
the
immersed surface.
ICG = 2nd moment of area of the immersed
surface
about the horizontal axis through CG
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12. MAJOR
EQUATION
Experimental determination of yp :
For equilibrium of the experimental apparatus,
moments about
the pivot P give
Fy = W.z
= M g. z
Where
y = Distance from
pivot to center of
pressure
M = Mass added to
hanger
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13. MAJOR
EQUATION
z = Distance from pivot to hanger
Therefore
y =
Mgz
F
But y = yp + r - y1 [ full submerged ]
y = yp = r + y1 [ partially submerged ]
Therefore
yp = y - (r - y1) [ fully submerged ]
yp = y - (r + y1) [ partially submerged ]
Where
r = Distance from pivot to top of
rectangular surface
y1 = Distance from water surface to top of
rectangular surface
In Fig
y2 = Distance from water surface to
bottom of rectangular surface
Fully submerged quadrant (c: centroid, p: center of pressure)
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14. • Partially submerged
quadrant (c: centroid, p:
center of pressure)
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15. PRACTICAL
APPLICATION
In engineering field, center of
pressure in most used topics. In our
practical life we used many things
which make on based of center of
pressure. Centre of pressure is also
used in Aircraft aerodynamics, Missile
aerodynamics etc.
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16. One very important application is for pitch
stability of an airplane. This is stability in the nose
up, nose down Direction. I use this when
designing paper airplanes.
• We look at the location between tail and nose of
both the center of gravity and the center of
pressure on the wing. The center of gravity is the
point where it appears that gravity is pulling
down on the aircraft.
• The center of pressure is a point along that line
where the lift is pulling up on the airplane.
PRACTICAL
APPLICATION
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17. Thank You very much
for your patience hearing
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